EP2012901B1 - Process and apparatus for removing coarse solids from a viscous fluid - Google Patents

Abstract

In a process for separating coarse solids (30) from a viscous fluid, especially from a sludge, the viscous fluid and the coarse solids (30) present therein are fed to a screening drum (4) which rotates about a horizontal or inclined axis (7). The viscous fluid passes through orifices (20) of the screening drum (4) which are arranged in a rotating outer casing (18) of the screening drum (4), and the coarse solids (30) are retained in the screening drum (4) and conveyed by a corrugated sheet (32) bonded to the rotating outer casing in the screen drum (4) to a discharge point of the screening drum (4). An apparatus for separating coarse solids (30) from a viscous fluid, especially from a sludge, has a screening drum (4) which is rotated about a horizontal or inclined axis (7). Orifices (20) are arranged in an outer casing (18) of the screening drum (4). A corrugated sheet (32) bonded to the rotating outer casing (18) is present in the screening drum (4). The rotating screening drum (4) is arranged in a fixed casing (2) which is bonded to a tank (22) for collecting the viscous fluid effluent.

Description

The present invention relates to a method for separating coarse solids from a viscous fluid, in particular from a sludge, and to an apparatus for carrying out this method.

The viscous fluid can be, for example, a sludge, as obtained in wastewater technology. In particular, it may be faecal sludge, the z. B. is sucked from domestic sewage treatment plants and is usually transported by tank vehicles to a facility where it is treated. The plant may be a sewage treatment plant or a special plant for the treatment of faecal sludge. Sewage sludge and fecal sludge is an aqueous suspension of more or less fine organic and mineral solids, which may also contain coarse solids such as sand, gravel or stones, which interfere with the treatment and cause high wear on the system components. Other coarse solids include paper, rags, and sanitary products such as sanitary napkins or condoms that can cause blockages or tears in the treatment facility.

On the other hand, however, the viscous fluid may also be industrially produced liquids containing coarse solids to be separated, for example, co-polymerized coarse solids in a monomer-containing liquid or a mineral suspension containing coarse solids such as Contains stones, or a biological suspension, for. B. a pulp from a fermentation.

In any case, the viscosity (viscosity) of such fluids is considerably higher than that of water, not the viscosity of the fluid itself, but the apparent viscosity or intrinsic viscosity of suspensions or emulsions.

It is known to use screening drums for separating coarse solids from wastewater. Screening drums are known which rotate about a horizontal or inclined axis and to which wastewater is passed which flows through openings of the screening drum arranged in a rotating jacket of the screening drum, the coarse solids being retained in the screening drum.

Described is such a separation device, for example in the US 3,401,801 A , To ensure that the cylindrically shaped screen drum is not clogged by existing solids, nozzles are provided, with the help of which a liquid can be injected from the outside onto the screen jacket.

Wastewater, however, is a comparatively low-solids fluid of low viscosity, which is only slightly higher than that of pure water. Therefore, wastewater flows through openings in the shell of the screen drum without great resistance. The coarse particles retained in the sieve drum are entrained by the rotation of the shell so as to detach at the apex and fall into an axially disposed trough, from which they are discharged axially by a rotating worm. With a high viscosity fluid, such screening drums function poorly because, on the one hand, the coarse particles adhere so firmly to the shell that they do not detach from it and fall into the trough, and, on the other hand, a large portion of the viscous fluid also rests against the jacket of the sieve drum sticks and gets into the trough, so that the degree of separation is very bad.

For this reason, for separating coarse substances from viscous fluids such as slurries stationary rake drums are used with circumferentially arranged slots, wherein the coarse solids retained at the slots are pushed by a rotating comb along the slots to the apex of the rake drum, where they through another fixed comb be detached from the rotating comb and fall into the axially disposed trough.

However, such fixed sieve drum have the disadvantage that they are picking especially by fibrous substances such as rags, hair or sanitary napkins, which in particular wrap around the rotating comb and its drive so that they are prone to failure and often have to be cleaned by hand. Another disadvantage is that the webs and combs are exposed to high wear caused by friction of sand and other mineral substances contained in the viscous fluid. Another disadvantage is that these fixed screening drums are usually arranged in cuboid closed containers to avoid odor emissions, so that sediments, especially sand and stones accumulate on the floor and in particular in the corners of the container and must be removed regularly, said the access to the closed containers is difficult.

It is also known to enter solid mixtures such as waste, compost or Straßenkehricht for the separation of coarse materials in a rotating drum screen on a front page. Small size solids fall through openings in the shell of the screen drum. A helical plate is connected to the rotating shell of the screen drum to promote the retained coarse material according to the principle of an Archimedean screw to the opposite end face and discharge there. However, such solid mixtures are not a fluid and not a suspension, even if the solid mixture is wet or this wash water is used to wash the retained coarse matter is supplied. These are more or less moist solids, but not a viscous fluid. Wash water, if added, is a low viscous liquid that easily drains through the openings of the screen drum.

From the US 2,983,378 a washing drum for cleaning and separating concrete components is known. The concrete is usually very uniform and can therefore be well divided into its components. The solid components are finally washed by means of a sprayer before they leave the drum. For the separation of coarse and in particular very different solids from a viscous fluid, as it is present in wastewater, this washing drum is not suitable. The solids in conjunction with the fluid would close the orifices of the washing drum very quickly.

The object of the present invention is to provide a method and a device for carrying out the method, in which the mentioned disadvantages of the prior art are avoided. In particular, a good degree of separation between the coarse solids and the viscous fluid should be achieved, in other words, that only slightly viscous fluid is discharged with the separated coarse materials. Furthermore, the method and the device should be simple, economical, reliable and low maintenance. The device should be low-wear and neither clog nor verzopfen.

The object is achieved by a method and a device having the features of the independent claims.

The viscous fluid and the coarse solids contained in a screen drum rotating about a horizontal or inclined axis are supplied in particular through an inlet-side end of the screen drum. The viscous fluid passes through arranged in a rotating jacket of the screen drum Openings of the screen drum and the coarse solids are retained in the screen drum and promoted by a connected in the screen drum with the rotating jacket helical plate to a discharge point, in particular to a discharge end of the screen drum. The solids can be ejected there. By a cleaning device, which acts on the screen drum, blockages and entanglements by the solids and the viscous fluid are reliably avoided. The cleaning device ensures that the openings of the sieve drum are not closed and the deposition takes place reliably even with the most difficult materials.

Although the individual elements of the method according to the invention are known for other applications, their combination and application for the separation of coarse matter from viscous fluids such as slurries offers particular advantages. The supply of the viscous fluid, for example through an end face of the screen drum avoids deposits of suspended matter in front of the screen drum and short-circuit flow. The rotation of the drum about its horizontal or inclined axis, the fluid fluid continuously free openings are fed to flow through. This is for example one of several differences to a centrifuge, which presses the material by its high speed to its peripheral wall. In the apparatus according to the invention, however, the material is usually always supplied to new openings. Gravity is stronger than centrifugal force.

If the axis of the sieve drum for discharge is increasing, so is facilitated by the height of the discharge of the discharge and the further promotion of the discharged coarse materials. The helical plate transports the retained coarse material to the discharge point in a gentle and low-wear manner, without the need for a special drive. The helical plate prevents fluid from flowing to the discharge point for the coarse materials. The helical metal sheet offers no approaches to fiber entanglements.

According to the invention, the coarse solids retained in the sieve drum are washed. As the washing liquid, the liquid phase of the fluid is normally used; For example, in faecal sludge, water is used as the scrubbing liquid since the liquid phase of sludge is water. By washing the retained coarse material, the degree of separation of the process is substantially improved, i. There are only very little fluid and contained impurities such as faeces discharged with the coarse materials.

The coarse solids are washed within the screen drum during their discharge and before their discharge. Preferably, the washing liquid drains through the openings in the jacket of the sieve drum. As a result, the additional cost of washing is kept very low and limited to the supply and splashing of the wash water.

In special cases, it is very advantageous if the elapsed washing liquid is collected and removed separately from the expired viscous fluid. As a result, a dilution of the fluid is avoided by running washing liquid, which is important, for example, when faecal sludge is fed directly to a sludge treatment, for. B. a digester. This feature is particularly important even if the washing liquid is not identical to the liquid phase of the viscous fluid, or if the fluid is a valuable material that should not be diluted by washing liquid.

According to a further embodiment of the invention, the coarse solids discharged from the screening drum are pressed in order to remove as much fluid or washing liquid as possible and to increase the solids content of the coarse materials. This can be done in a wash press of known type. Advantageously, the method according to the invention enables the viscous fluid and the coarse solids contained in it to be fed to the screen drum in batches. In particular, fecal sludge is delivered in batches in tank trucks, and it is important to be able to quickly empty the tank vehicles to reduce their residence time. The inflow-side gaps between the helical plate can be filled with a large volume in a short time, wherein the supplied viscous fluid fills one space after another, without it being possible for a flow of fluid to the discharge end of the screen drum. As the filled spaces gradually move towards the discharge of coarse matter, the viscous fluid flows through the openings in the shell. Accordingly, the method of the invention is excellently suited to withstand peak loads by rapid loading of large batches.

The process according to the invention is particularly suitable for liberating a viscous fluid having a dynamic viscosity or apparent dynamic viscosity between 0.01 and 1 Pa.s, preferably between 0.02 and 0.2 Pa.s of coarse materials. A suspension or emulsion having an apparent viscosity in said ranges behaves in a viscometer as well as a liquid whose viscosity is also high. The said range of viscosities is 10 to 100 times that of pure water at 20 ° C. Although the method according to the invention is also suitable for fluids of lower viscosity, the advantages of the method according to the invention over the prior art methods are particularly pronounced in the case of highly viscous fluids. For fluids whose viscosity is above the stated range, the method according to the invention is also unsuitable, since a good flow of the fluid under the effect of gravity through the openings in the jacket is then no longer possible.

The inventive method is particularly suitable for a viscous fluid having a solids content between 0.5 and 6%. Sludges whose solids concentration is in this range have a dynamic viscosity for which the method according to the invention is particularly advantageous in comparison with the prior art.

Preferably, the screen drum is pressurized with the coarse solids and the viscous fluid. Solids and fluid are thereby introduced specifically into the sieve drum. The separation is easier and a clogging of the feed pipe is avoided.

The method is preferably realized using a device, wherein the rotating screen drum is arranged in a fixed housing, which is connected to a trough for collecting the draining viscous fluid. The housing serves to prevent the emission of odor, vapor and aerosols from the fluid and wash water. The effluent through the openings of the shell of the screen drum fluid is collected in the tub, which is preferably an integral part of the housing. With the cleaning device, the function of the drum is ensured even with difficult solids and fluids.

According to the invention, at least one spray nozzle for washing the retained coarse solids is arranged within the screen drum to allow additional washing of the retained coarse materials with little additional effort. Here, the spray nozzle for washing the coarse solids is arranged in a range between half the length of the screen drum and the discharge end. This means that at least the first half of the screening drum is used for screening and less than the second half for washing the coarse materials.

Advantageously, the trough has a low point at which an outlet opening, in particular a nozzle, is arranged in order to drain off the outflowing fluid. In a further advantageous embodiment of the device according to the invention the housing is connected to a second trough for collecting washing liquid with a low point at which a second outlet opening, in particular a second nozzle for the effluent washing liquid is arranged, wherein the second trough viewed from the inflow end is arranged behind the first tray for collecting the expiring viscous fluid. This embodiment is particularly advantageous if the fluid is not mixed mixed with washing liquid and diluted. The second tray is used for separate collection of the washing liquid.

The housing of the device according to the invention may have a connection for a line for sucking off gases and vapors, in order to supply them to a treatment, which is particularly advantageous when liberated gases or vapors are hazardous to health. For example, the hydrogen sulfide leaving faecal sludge is not only very odor-intensive but even toxic in very low concentrations. The treatment can be carried out, for example, by acidic or alkaline washing or in a biofilter. When air is extracted from the housing, a slight negative pressure is created within the housing to prevent gases and vapors from escaping into the environment through leaks in the housing.

If the screen drum is provided with a drive which rotates it at a speed between 2 and 100 revolutions per minute, a very effective screening is effected. The principle of action differs from a centrifuge, which presses the material against the jacket of the drum at a much higher speed.

Preferably, the device is made of corrosion resistant materials such as stainless steels. Corrosion is generated by moisture, but especially by released gases. For example, the combination of condensed water and hydrogen sulphide forms extremely corrosive sulfuric acid. By contrast, stainless steel with the material number 1.4571 (SS 316), for example, is relatively resistant. Corrosion resistance can also by coating the materials, eg. B. with suitable plastic can be achieved.

In an advantageous embodiment, the axis of the drum has an angle to the horizontal of 3 to 30 °, preferably from 5 to 15 °. In particular, the axis increases from the inlet end to the discharge end. The coarse materials are transported by the helical plate obliquely up to the discharge end, whereas the viscous fluid can flow back through interruptions in the helical plate to the inlet end. Lower angles offer no advantage over a horizontal axis, larger angles would reduce the volume of fluid between the coil plate too much.

Advantageously, the openings in the jacket of the rotating screen drum perforations with a diameter between 3 and 15 mm, preferably between 6 and 10 mm. Holes hold back the coarse material better than gaps or slits. Elongated coarse materials are better retained in screens with holes or mesh than by screens with gaps. In particular for sewage and faecal sludge, the said range is favorable for the hole diameter, because the faeces pass through, while coarse contaminants are retained. Smaller openings would be too clog-prone, larger openings would let too many contaminants through.

Alternatively, the openings in the shell of the rotating screen drum slots with a gap width of 2 to 12 mm, preferably from 4 to 8 mm. Slots or gaps must have a smaller width than holes around them To provide support. For this, the free area Spaltsieben is usually greater than that of perforated screens.

In a further embodiment of the device according to the invention, at least part of the jacket of the screen drum has wedge-shaped webs arranged in parallel, between which the slots extend, wherein the webs on the inner surface of the shell are wider than on the outer surface of the shell. It may well be advantageous if only a part of the shell is provided with slots and another part with differently shaped openings, for. B. with holes. The shape of the column defining ridges causes the gaps to be narrower on the inner surface of the shell than on its outer surface. This will prevent solids from wedging in the slots and clogging the slots.

Preferably, the slots are arranged annularly about the axis of the screen drum, i. in the direction of the circumference of the sieve drum. As a result, the cleaning of the screen drum z. B. relieved by brushing.

In a further advantageous embodiment of the device according to the invention, at least one spray nozzle for cleaning the openings in the jacket of the screening drum is arranged inside the housing and outside the screen drum. The fuel nozzle is thus located in the cavity between the housing and the screen drum. The spray nozzle is arranged above the axis of the screening drum. The nozzle injects washing liquid onto the jacket against the direction of flow of the fluid to remove solids from the openings and clear the openings.

The at least one spray nozzle is preferably arranged in a position between 8 and 12 o'clock when the sieve drum rotates clockwise when viewed from the inlet-side end face of the sieve drum. In the direction of rotation of the screen drum, the spray nozzle is thus arranged in front of the vertex. The mantle and its openings are washed as soon as they reach the area in which the viscous fluid is sifted upwards. The jets of the spray nozzle are preferably directed downwardly to facilitate drainage of liquid and the contaminants contained therein. In most cases, several spray nozzles are arranged on a spray nozzle bar, which runs parallel to the axis of the sieve drum.

In order to further improve the cleaning of the openings in the shell, it is advantageous to arrange at least one further spray nozzle in a position between 12 and 4 o'clock, ie after the apex, in order to further improve the cleaning of the openings in the shell. Also, this nozzle preferably injects downward or obliquely downward. This nozzle may also be part of a spray nozzle strip arranged parallel to the axis of the sieve drum.

Preferably, the spray nozzles washing liquid is supplied at a pressure between 2 and 10 bar, so that the speed of the beam is 20 to 45 m / s. When the viscous fluid is an aqueous suspension or emulsion, preferably water, e.g. B. clear water, used as a washing liquid.

Additionally or alternatively, at least one high-pressure spray nozzle for cleaning the openings in the jacket of the screen drum can be arranged inside the housing and outside the screen drum. High pressure spray nozzles may be required in particular if the openings in the jacket of the screen drum are small or if the viscous fluid or coarse solids are very sticky. The use of high-pressure nozzles has the advantage that their cleaning effect is very good despite very low consumption of washing liquid. The high-pressure spray nozzle may be arranged instead of or in addition to the aforementioned spray nozzles, preferably also in a position where it squirts down or obliquely downward.

In particular, a plurality of high-pressure nozzles are arranged on a straight line parallel to the axis of the screen drum with a spacing between the high-pressure nozzles of from 5 to 50 cm, preferably from 10 to 30 cm. This ensures that the entire lateral surface passes through the sphere of action of the high pressure spray nozzles.

In a particularly advantageous embodiment, the at least one high-pressure spray nozzle in the axial direction, that is parallel to the axis of the screen drum, movable. As a result, the range of action of the spray nozzle is increased. It is sufficient if the high-pressure washing liquid jet reaches every point of the drum shell from time to time. With a coordinated combination of the axial movement of the high pressure spray nozzle and the rotating movement of the shell, the entire shell surface is periodically subjected to high pressure jets.

In a further embodiment of the device according to the invention, the at least one Hochdruckspritzdüse by means of a spindle gear is movable. The spindle gear consists of a rotatably driven threaded rod or spindle which extends through a correspondingly threaded holder of the nozzle. Upon rotation of the threaded rod, the holder and with it the nozzle moves in the axial direction of the threaded rod. By reversing the direction of rotation of the threaded rod, the axial direction of movement of the carrier and the nozzle is reversed. The spindle is arranged coaxially with the axis of the screening drum.

The at least one high-pressure spray nozzle is preferably supplied with washing liquid at a pressure between 50 and 300 bar, so that the velocity of the washing-liquid jet is 100 to 250 m / s.

Alternatively or in addition to the spray nozzles, at least one brush for cleaning the openings in the jacket of the screening drum outside the screen drum be arranged. The bristles of the brush engage in the openings in the basket drum to press solids from the openings. The brush is preferably arranged in the direction of rotation behind a spray nozzle, so that it is not contaminated by viscous fluid. Their task is to push solids still stuck in openings of the shell out of the openings.

According to a particularly advantageous embodiment of the invention, the brush is cylindrical and rotates about its axis. The bristles of a rotating cylindrical brush engage deeper and longer in the openings in the shell of the rotating screen drum so that they have a better cleaning effect than the bristles of a fixed brush. In addition, the bristles wear less as the brush rotates.

The cleaning effect is particularly good and the wear of the bristles is particularly low when the brush rotates at approximately the same peripheral speed as the drum of the drum.

Preferably, the brush is drivable by the screen drum. This ensures that the brush has almost the same peripheral speed as the screen drum. In addition, a motor to drive the brush is unnecessary, which reduces the manufacturing and operating costs. The drive of the brush on the screen drum is positive or non-positive on the brushes.

In a further advantageous embodiment of the invention, the device is connected to a pipe for supplying the viscous fluid, the pipe is inserted through the inflow-side end in the screen drum and has an end within the screen drum, wherein the end of the pipe at an angle between 30 ° and 90 ° to the axis of the screen drum, so that the supplied fluid flows out with a radial velocity component of the end of the pipe. The supplied fluid hits with a Radial velocity component on the shell, so that the fluid flows with kinetic energy through the openings in the jacket. This kinetic energy also creates turbulence that removes solids from the openings. Preferably, the screen drum is pressurized with the coarse solids and the viscous fluid. Solids and fluid are thereby introduced specifically into the sieve drum. The separation is easier and a blockage of the pipeline is avoided. Feeding under pressure can also be done with a pipe without a curved end, although the curvature is more successful.

Preferably, the pipeline is approximately parallel to the axis of the screen drum or horizontally inserted into the screen drum, and the end of the pipeline is a pipe bend. It has manufacturing advantages when the tubing is fed axially or coaxially with the axis of the drum vertically through a surface of the housing. On the other hand, the connection of the pipeline is easier if it runs horizontally. To create a radial velocity component, a pipe bend is placed at the end of the pipe.

Advantageously, the radial velocity component points in one direction between 6 and 9 o'clock when the sieve drum rotates clockwise when viewed from the inlet end. This means that the fluid supplied impinges at a location on the shell of the screen drum, where the shell moves up and openings are added by solids. The impinging fluid flushes openings.

To avoid too high a velocity of the introduced fluid, the end of the tubing has a diameter that is 1.25 to 3 times the diameter of the feeding tubing. As a result, the velocity of the fluid at the end is reduced to about 11 to 64% of the velocity in the pipeline. This is particularly advantageous for a supply of large batches in a short time, ie at very high Speed in the pipeline. By reducing the velocity of the fluid as it leaves the end of the tubing, damage to the screen drum and filament plate caused by too sharp a jet is avoided.

In a further embodiment of the invention, the end of the pipe has a cross-sectional area which is increased so that the viscous fluid at a speed between 0.5 and 3 m / s, preferably between 0.75 and 2 m / s in the screen drum flows. This is a speed sufficient to prevent sedimentation but not so great as to damage the screen drum.

In a further advantageous embodiment of the invention, the helical plate in the sieve drum in the region of the openings in the shell of the sieve drum no interruption. This means that the sheet consists of one piece in the region of the openings, so that the sheet forms closed weirs, which prevent the passage of fluid to the discharge end of the screen drum.

Preferably, the helical plate in the sieve drum 5 to 15 helices, so that the passage of the fluid is repeatedly prevented by acting as a weir coils of the sheet. The longer the screen drum, the more coils are provided.

The helical plate has, in a further embodiment of the invention, a height between 5 and 25% of the diameter of the screening drum. The larger this ratio, the greater the volume of fluid in the spaces between the coils, the greater the maximum throughput of the viscous fluid. On the other hand, an even greater height of the helical plate would hinder the arrangement and installation of spray nozzles in the sieve drum.

According to a further preferred embodiment of the invention, the sheath within a distance of 5 mm behind the helical plate, seen from the inlet end of the sieve drum, no openings. This prevents the sheet from shrinking the free cross-sectional area of openings in the immediate vicinity of the sheet and that settle there solids such as fibers. Where the helical sheet passes, no holes are punched, drilled or cut in the shroud of the screen drum.

Preferably, the screen drum rotates at a speed between 2 and 100, preferably between 2 and 20 revolutions per minute, in particular between 3 and 10 revolutions per minute. Although a low speed increases the maximum fluid flow rate, but reduces the throughput of coarse solids and the frequency with which the openings are washed.

In a further embodiment of the invention, the speed of the drum is variably adjustable in order to optimize the ratio between the maximum flow rates for fluid and coarse materials.

Preferably, the screen drum is mounted radially on its circumference on rollers connected to the housing. As a rule, two rollers are arranged near the inlet-side end and two further rollers near the discharge-side end. As a result, the screen drum requires no shaft and their storage. The storage preferably takes place over the outer surface of the sieve drum.

According to a further preferred embodiment, the screening drum has an inlet-side end face, which is mounted axially by means of at least one roller. If the screen drum at the discharge end is higher, this role is attached to the upstream side face. All roles are outside arranged the fluid area, so that the function of the rollers is not affected by contamination.

The sieve drum can be driven by a motor via a pinion and a ring gear. It is even more advantageous if the screening drum can be driven by a motor via a pinion and a chain, wherein the chain is fastened to the circumference of the screening drum and the pinion engages in links of the chain. This eliminates the cost of a sprocket and a chain tensioner.

In a further embodiment of the invention, the trough for collecting the viscous fluid has a bottom which has a slope of at least 25 ° to the horizontal in order to avoid deposition of solids in the trough. In order to avoid the deposition of sand and other mineral sediments, a slope of at least 45 ° is required.

In a further embodiment of the device according to the invention, the jacket of the screen drum has a surface area between 0.2 and 0.4 m ² per 1 / s inflow of the viscous fluid. This means that 5 to 10 l / s of the viscous fluid can be supplied per m ² lateral surface of the sieve drum.

Figur 1

einen schematisch dargestellten Längsschnitt durch eine erfindungsgemäße Vorrichtung zum Abtrennen von groben Feststoffen aus einer viskosen Flüssigkeit entlang der Achse einer rotierenden Siebtrommel,

Figur 2

einen schematisch dargestellten Querschnitt durch die erfindungsgemäße Vorrichtung der Figur 1 senkrecht durch die Achse der rotierenden Siebtrommel und deren Lagerung,

Figur 3

einen weiteren schematisch dargestellten Querschnitt durch die erfindungsgemäße der Figur 1 senkrecht durch die Achse der rotierende Siebtrommel und deren Antrieb,

Figur 4

eine Detailansicht von zwei erfindungsgemäßen, mittels eines Spindeltriebes bewegbaren Hochdruckspritzdüsen.

Further features and advantages of the invention can be found not only in the claims but also in the following exemplary embodiments and the figures illustrating them. In the figures, the same or equivalent elements are designated by identical reference numerals. Show it

FIG. 1

a schematically illustrated longitudinal section through an inventive device for separating coarse solids from a viscous liquid along the axis of a rotating screen drum,

FIG. 2

a schematically illustrated cross section through the inventive device of FIG. 1 perpendicular through the axis of the rotating screen drum and its storage,

FIG. 3

a further schematically illustrated cross section through the invention of FIG. 1 perpendicular to the axis of the rotating screen drum and its drive,

FIG. 4

a detailed view of two inventive, movable by means of a spindle drive high pressure spray nozzles.

In FIG. 1 an apparatus according to the invention for separating coarse solids from a viscous liquid is shown. The device has a housing 2, in which a screening drum 4 is arranged. The screen drum 4 has an inlet-side end 5 and an outlet-side end 6 and is rotatable about an axis 7. In the exemplary embodiment, the axis 7 is inclined to the horizontal so that the discharge-side end 6 is higher than the inlet-side end. 5

Viscous fluid is supplied to the device through a pipe 8. The pipe 8 passes through an end wall 10 of the housing 2. In the example, an axis 12 of the pipe 8 is shown at an angle to the axis 7 of the screen drum 4, but the axes 12 and 7 can also be parallel. The pipe 8 has an extension 14 to reduce the velocity of the incoming viscous fluid. At the end of the pipe 8 a pipe bend 16 is mounted to change the direction of the incoming viscous fluid so that it flows with a radial component relative to the axis 7 of the screen drum 4 from the pipe 8. The illustrated pipe bend 16 has an angle of 45 °.

The sieve drum 4 has a jacket 18 which is provided with openings 20. Under the influence of gravity, the fluid flows through the openings 20 through and is collected in a connected to the housing 2 well 22. The tub 22 has a bottom 24 which has a slope of at least 25 °, so that the fluid drains to a low point 26 and solids contained in the fluid do not deposit on the bottom 24. At the low point 26, a nozzle 28 is arranged through which the fluid is discharged.

The openings 20 may be round, rectangular or slot-shaped. Coarse solids 30, which are larger than the openings 20, are retained at the openings 20 and remain in the screening drum 4. The inner shell 18 of the screening drum 4, a helical plate 32 is attached. The helical plate 32 is helical. The helical plate 32 may have interruptions to allow backflow of the fluid in the screen drum 4 toward the upstream end 5. The helical plate 32 may also be interruption free. By rotation of the spiral drum 32 connected to the screen drum 4, the retained coarse materials 30 are transported to the discharge end 6 and fall there through a housing connected to the shaft 34. The discharged coarse materials can be collected in a container, not shown, or further promoted with a conveyor, not shown become. They may be subjected to further treatment by washing or pressing.

In the housing 2, outside the screen drum 4 and above the axis 7 spray nozzles 36 are mounted on a parallel to the axis 7 arranged spray nozzle 37. The spraying nozzles 36 are supplied with washing liquid, for example washing water, via a line 38. While the jacket 18 rotates past the spray nozzles, the spray nozzles 36 spray the washing liquid onto the jacket 18 from the outside, so that solids adhering to the openings 20 are washed back into the screening drum 4 and the openings 20 are free again when they are lowered again rotate where they are re-pressurized with fluid.

In the housing 2, within the screen drum 4 and below the axis 7 further spray nozzles 40 are mounted on a further parallel to the axis 7 arranged spray nozzle 42. The spray nozzles 40 washing liquid is supplied via a further line 44. The spray nozzles 40 inject washing liquid onto coarse materials retained in the screen drum 4 to wash away viscous fluid or contaminants such as feces adhered thereto while the coarse materials are transported to the discharge side end 6 of the screen drum 4. Below the spray nozzles 40 a further connected to the housing 2 trough 46 is arranged for collecting washing liquid. The tub 46 has a bottom 48 that is inclined at least 25 ° to a bottom 50 to prevent deposits of solids. At the low point 50, a nozzle 52 is arranged for discharging the washing liquid. The washing liquid supplied to the spray nozzles 40 and discharged via the nozzle 52 may be other than that supplied to the spray nozzles 36. By disposing the second tub 46, the viscous fluid collected in the first tub 22 is prevented from being diluted with the washing liquid supplied to the spray nozzles 40.

On top of the housing 2, a further nozzle 54 is arranged for the suction of gases and vapors, which can be supplied to a treatment. By sucking air, a slight negative pressure is generated in the housing 2, which prevents odor and steam from leaking through leaks in the housing 2.

A connected to the housing 2 roller 56 runs on an end face 58 of the screen drum 4, so that the screen drum 4 is axially supported by the roller 56 and not in the direction of the inlet end 5 is movable.

FIG. 2 shows a cross section through the device according to the invention perpendicular to the axis 7 of the screen drum 4. The device is viewed from the inlet end 5 of the screening drum 4 from. The sieve drum 4 rotates in a clockwise direction about the axis 7. The screening drum 4 is mounted on rollers 60 and 62, which are connected to the housing 2. The helical plate 32 has a height of 5% to 25% of the diameter of the shell 18 of the sieve drum 4th

The viscous fluid is supplied through the pipe 8, the extension 14 of the pipe 8 and a pipe bend 16 attached to the end of the pipe 8. The pipe bend is oriented so that the fluid flows into the screen drum 4 with a radial velocity component pointing in the direction of 8 o'clock. There, the jacket 18 moves upward and its openings 20 are partially plugged with solids. The fluid is there on the jacket 18 of the screen drum 4 and flushes the clogging solids from the openings 20 away.

The spray nozzles 36 are arranged in this example in a position of about 11 o'clock, so that the washing liquid flows inside the jacket 18. Further spray nozzles 64 are arranged in a position of about 2 o'clock to further improve the cleaning of the openings 20. In the housing 2 and outside the screen drum 4, a brush roller 66 is arranged coaxially with the axis 7 of the screen drum 4. Brushes 68 of the brush roller 66 engage the openings 20 and push solids back from the openings into the screen drum. The brush roller 66 rotates counterclockwise. The brush roller 66 is driven by the movement of the shell 18 by entraining into the openings engaging brush 68.

FIG. 3 shows a further cross section through the device according to the invention in the region of the drive of the screen drum 4. A chain 70 is circumferentially mounted on the jacket 18 of the screen drum 4. The teeth of a pinion 72 engage members of the chain 70. The pinion is driven by a motor via a shaft 74. The shaft 74 is parallel to the axis 7th arranged the screening drum 4. An expensive sprocket and a chain tensioning device are not required.

FIG. 4 shows two movable high pressure spray nozzles 80 and 82 for use in the device according to the invention. High pressure spray nozzles are placed at the same position instead of normal spray nozzles to further enhance the cleaning of the openings 20 of the screen basket 4 and to reduce the consumption of wash liquid. The high pressure nozzles 80 and 82 are secured to brackets 84 and 86. Washing liquid is supplied via hoses 88 and 90. The movable brackets 84 and 86 are guided by a stationary rod 92. The rod 92 extends through holes in the brackets 84 and 86. The stationary rod prevents the brackets 84 and 86 from rotating. The holders 84 and 86 have further holes with internal thread through which a spindle 94 extends with matching external thread. The spindle 94 is disposed parallel to the axis of the screening drum and connected to a drive which sets it in rotation about its axis 96. As the spindle 94 rotates, the brackets 84 and 86 move at an identical speed in the axial direction. With a suitable combination and coordination of the speeds of axial movement of the brackets 84 and 86 and the rotation of the screen drum 4, the high-pressure nozzles clean the entire jacket 18 of the screen drum 4.

The invention is not limited to the illustrated embodiments. Modifications within the scope of the claims are possible at any time.

Claims (15)

1. A method for precipitating coarse solids (30) out of a viscous fluid, particularly out of a sludge, the viscous fluid and the coarse solids (30) present therein being fed into a screen drum (4) rotating about a horizontal or tilted axis (7) through a first end face of the screen drum (4), the viscous fluid running off through openings (20) of the screen drum (4) disposed in a rotating shell (18) of the screen drum (4) and being collected by means of a pan (22) connected to a stationary housing (2) in which the rotating screen drum (4) is disposed, the coarse solids (30) being retained in the screen drum (4) and transported by means of a helical sheet metal (32) connected to the rotating shell (18) in the screen drum (4) to a discharge point at a second end face of the screen drum (4), and the screen drum (4) being cleaned by a cleaning device, characterized in that the coarse solids (30) retained in the screen drum (4) are washed during the discharge thereof in the region between half the length of the screen drum (4) and the discharge point by means of at least one spray nozzle (40) disposed within the screen drum (4).
2. The method according to the preceding claim, characterized in that the washing fluid introduced by means of the spray nozzle (40) runs off through the openings (20) in the shell (18) of the screen drum (4).
3. The method according to one or more of the preceding claims, characterized in that the viscous fluid comprises a dynamic viscosity or apparent dynamic viscosity between 0.01 and 1 Pa*s, preferably between 0.02 and 0.2 Pa*s, and/or the viscous fluid comprises a solids content between 0.5% and 6%.
4. A device for precipitating coarse solids (30) out of a viscous fluid, particularly out of a sludge, the device comprising a screen drum (4) rotating about a horizontal or tilted axis (7), openings (20) of the screen drum (4) being disposed in a shell (18) of the screen drum (4), a helical sheet metal (32) being connected to the rotating shell (18) in the screen drum (4), the rotating screen drum (4) being disposed in a stationary housing (2) connected to a pan (22) for collecting the viscous fluid running off, a feed device for the viscous fluid and the coarse solids (30) present therein being disposed at a first end face of the screen drum (4) and a discharge device for the coarse solids (30) being disposed at a second end face of the screen drum (4), and the screen drum (4) being associated with a cleaning device, characterized in that at least one spray nozzle (40) is disposed in a region between half the length of the screen drum (4) and the second end face thereof for washing the retained coarse solids (30).
5. The device according to the preceding claim, characterized in that the pan (22) comprises a low point (26) at which an outlet opening, particularly a fitting (28), is disposed for the fluid running off, and/or the housing (2) is connected to a second pan (46) for collecting washing fluid and having a low point (50), at which a second outlet opening, particularly a second fitting (52), is disposed for the washing fluid running off, wherein the second pan (46) is disposed behind the first pan (22) for collecting the viscous fluid running off, as seen from an inlet end (5).
6. The device according to one or more of the claims 4 and 5, characterized in that the housing (2) comprises a connection (54) for drawing off gases and vapors.
7. The device according to one or more of the claims 4 through 6, characterized in that the openings (20) in the shell (18) of the rotating screen drum (4) are perforations having a diameter between 3 and 15 mm, preferably between 6 and 10 mm.
8. The device according to one or more of the claims 4 through 7, characterized in that the openings (20) in the shell (18) of the rotating screen drum (4) are particularly annular slits disposed about the axis (7) of the screen drum (4) and having a gap width of 2 to 12 mm, preferably of 4 to 8 mm.
9. The device according to one or more of the claims 4 through 8, characterized in that at least one spray nozzle (36) for cleaning the openings (20) in the shell (18) of the screen drum (4) is disposed within the housing (2) and outside of the screen drum (4), particularly in a position between 8 and 12 o'clock when the screen drum (4) rotates clockwise as seen from the end face of the screen drum (4) on the inlet side.
10. The device according to the preceding claim, characterized in that at least one further spray nozzle (64) is disposed in a position between 12 and 4 o'clock.
11. The device according to one or more of the claims 9 and 10, characterized in that washing fluid is fed to the at least one spray nozzle (36) at a pressure between 2 and 10 bar.
12. The device according to one or more of the claims 4 through 11, characterized in that at least one brush (68) for cleaning the openings (20) in the shell (18) of the screen drum (4) is disposed outside of the screen drum (4).
13. The device according to one or more of the claims 4 through 12, characterized in that the end of the pipeline (8) comprises a diameter that is 1.25 to 3 times as large as the diameter of the inlet pipeline (8) in order to reduce the speed of the incoming fluid.
14. The device according to one or more of the claims 4 through 13, characterized in that the rotational speed of the screen drum (4) can be adjusted variably.
15. The device according to one or more of the claims 4 through 14, characterized in that the shell (18) of the screen drum (4) comprises a surface area between 0.2 and 0.4 m² per Us of infeed of the viscous fluid.

Images